The present invention relates to air-relief valves such as are used for releasing air from water pipelines.
There are two basic types of air relief valves, namely the single-orifice type and the double-orifice type. One form of the single-orifice type (commonly called a "kinetic" air relief valve) includes a large orifice for releasing or admitting large volumes of air during water filling or draining operations of the pipeline; a second form of the single-orifice type (commonly called an "automatic" air relief valve) includes a small orifice for releasing air accummulated under pressure in the pipeline during normal operating conditions. The double-orifice type is a combined unit including two single orifice valves, namely a kinetic large-orifice valve and an automatic small-orifice valve, the unit having a common connection to the pipeline.
Many forms of air-relief valves of both the single-orifice type and the double-orifice type are now commercially available. One form, particularly useful as a double-orifice valve, includes two bell-shaped floats, one nestable within the other, the outer float cooperating with the large orifice formed in the valve housing, and the inner float cooperating with a small orifice formed in the outer float. Such a nesting, two-float arrangement enables a very compact construction to be attained for a valve having a relatively high air-release capacity and a capability of operating under high pipeline pressures.
An object of the present invention is to provide a new form of air-release valve which can be constructed even more compactly for a given air-release capacity and pressure operating conditions of the pipeline.